RESEARCH OBJECTIVES: The purpose of this program is to develop an understanding of the mechanical properties of the growing skeleton in children. Of basic interest are the mechanical parameters which describe skeletal strength. Two techniques will be employed. The first will determine the bone geometry in the growing skeleton as well as its mechanical tissue properties. These will be combined in an engineering analysis to predict bone strength levels. The second technique involves the direct measurement of bone strength in a comparison to the model prediction. Tissue properties and bone geometry and whole bone strength will be obtained from autopsy specimens.